Long Term Objective: The major goal of this research is to determine the effectiveness of amoxicillin prophylaxis in the management of children with recurrent episodes of otitis media. This information is needed to develop clinical practice guidelines. Health Relatedness: Management of recurrent otitis media is an appropriate condition for study for the following reasons: 1) Large numbers of children experience recurrent otitis media; 2) physicians differ widely in their choice of alternative medical and surgical interventions; and 3)health care expenditures associated with the management of recurrent otitis media are substantial. Experimental Design: This is a prospective randomized double blinded controlled clinical trial that compares the effectiveness of continuously administered once or twice daily amoxicillin to a placebo in the prevention of new episodes of otitis media. The specific hypotheses that will be tested are: 1) the frequency of new episodes of otitis media in children given a placebo twice daily for a period of three to four months will be at least 50% greater than that in children given 10 mg per kg body weight of amoxicillin administered twice daily during the same period of time; 2) the frequency of new episodes of otitis media in children given a placebo for three to four months will be at least 25% greater than that in children given amoxicillin administered once daily in a dose of 20 mg per kg body weight during the same period of time; and 3) the frequency of new episodes of otitis media in children given once daily amoxicillin in a dose of 20 mg per kg body weight will be at least 33% greater than that in children given amoxicillin in a dose of 10 mg per kg body weight twice daily during a three to four month period of time. Pneumatic otoscopy and tympanometry will be used to determine the presence of middle ear effusion. Compliance will be monitored with a medication diary, measurement of unused medication, and urine antibiotic screening. Outcome measures will include incidence density rates of new otitis episodes per months at risk and proportion of subjects per group without new otitis episodes. Subjects who develop 2 new otitis episodes or have a persistent middle ear effusion 8 weeks or longer despite two courses of antibiotics will be discontinued from the study.